﻿using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace WPFNote.Utilities.Common
{
    /// <summary>
    /// 加密帮助类。
    /// </summary>
    public static class EncryptionHelper
    {
        #region MD5
        /// <summary>
        /// MD5加密。
        /// </summary>
        /// <param name="enystr">要加密的字符串。</param>
        /// <returns>加密完毕的字符串。</returns>
        public static string Md5(string enystr)
        {
            using (MD5 mi = MD5.Create())
            {
                byte[] buffer = Encoding.Default.GetBytes(enystr);
                //开始加密
                byte[] newBuffer = mi.ComputeHash(buffer);
                StringBuilder sb = new StringBuilder();
                for (int i = 0; i < newBuffer.Length; i++)
                {
                    sb.Append(newBuffer[i].ToString("x2"));
                }
                return sb.ToString().ToLower();
            }
        }
        #endregion

        #region RSA

        /// <summary>
        ///  生成密钥对。
        /// </summary>
        /// <param name="xmlKeys">返回的私钥</param>
        /// <param name="xmlPublicKey">返回的公钥</param>

        public static void RSAKey(out string xmlKeys, out string xmlPublicKey)
        {
            System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            xmlKeys = rsa.ToXmlString(true);
            xmlPublicKey = rsa.ToXmlString(false);
        }


        /// <summary>
        /// RSA加密
        /// </summary>
        /// <param name="rawInput"></param>
        /// <param name="publicKey"></param>
        /// <returns></returns>
        public static string RsaEncrypt(string rawInput, string publicKey)
        {
            if (string.IsNullOrEmpty(rawInput))
            {
                return string.Empty;
            }

            if (string.IsNullOrWhiteSpace(publicKey))
            {
                throw new ArgumentException("Invalid Public Key");
            }

            using (var rsaProvider = new RSACryptoServiceProvider())
            {
                var inputBytes = Encoding.UTF8.GetBytes(rawInput);//有含义的字符串转化为字节流
                rsaProvider.FromXmlString(publicKey);//载入公钥
                int bufferSize = (rsaProvider.KeySize / 8) - 11;//单块最大长度
                var buffer = new byte[bufferSize];
                using (MemoryStream inputStream = new MemoryStream(inputBytes),
                     outputStream = new MemoryStream())
                {
                    while (true)
                    { //分段加密
                        int readSize = inputStream.Read(buffer, 0, bufferSize);
                        if (readSize <= 0)
                        {
                            break;
                        }

                        var temp = new byte[readSize];
                        Array.Copy(buffer, 0, temp, 0, readSize);
                        var encryptedBytes = rsaProvider.Encrypt(temp, false);
                        outputStream.Write(encryptedBytes, 0, encryptedBytes.Length);
                    }
                    return Convert.ToBase64String(outputStream.ToArray());//转化为字节流方便传输
                }
            }
        }

        /// <summary>
        /// RSA解密
        /// </summary>
        /// <param name="encryptedInput"></param>
        /// <param name="privateKey"></param>
        /// <returns></returns>
        public static string RsaDecrypt(string encryptedInput, string privateKey)
        {
            if (string.IsNullOrEmpty(encryptedInput))
            {
                return string.Empty;
            }

            if (string.IsNullOrWhiteSpace(privateKey))
            {
                throw new ArgumentException("Invalid Private Key");
            }

            using (var rsaProvider = new RSACryptoServiceProvider())
            {
                var inputBytes = Convert.FromBase64String(encryptedInput);
                rsaProvider.FromXmlString(privateKey);
                int bufferSize = rsaProvider.KeySize / 8;
                var buffer = new byte[bufferSize];
                using (MemoryStream inputStream = new MemoryStream(inputBytes),
                     outputStream = new MemoryStream())
                {
                    while (true)
                    {
                        int readSize = inputStream.Read(buffer, 0, bufferSize);
                        if (readSize <= 0)
                        {
                            break;
                        }

                        var temp = new byte[readSize];
                        Array.Copy(buffer, 0, temp, 0, readSize);
                        var rawBytes = rsaProvider.Decrypt(temp, false);
                        outputStream.Write(rawBytes, 0, rawBytes.Length);
                    }
                    return Encoding.UTF8.GetString(outputStream.ToArray());
                }
            }
        }
        #endregion

        #region DES
        public static readonly string DESKey = "splcd.co";
        /// <summary>
        /// 进行DES加密。
        /// </summary>
        /// <param name="pToEncrypt">The p to encrypt.</param>
        /// <param name="sKey">The s key.</param>
        /// <returns></returns>
        public static string Encrypt(string pToEncrypt, string sKey)
        {
            using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
            {
                byte[] inputByteArray = Encoding.UTF8.GetBytes(pToEncrypt);
                des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
                des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(inputByteArray, 0, inputByteArray.Length);
                    cs.FlushFinalBlock();
                    cs.Close();
                }
                string str = Convert.ToBase64String(ms.ToArray());
                ms.Close();
                return str;
            }
        }


        /// <summary>
        ///进行DES解密。
        /// </summary>
        /// <param name="pToDecrypt">The p to decrypt.</param>
        /// <param name="sKey">The s key.</param>
        /// <returns></returns>
        public static string Decrypt(string pToDecrypt, string sKey)
        {
            byte[] inputByteArray = Convert.FromBase64String(pToDecrypt);
            using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
            {
                des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
                des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                using (CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(inputByteArray, 0, inputByteArray.Length);
                    cs.FlushFinalBlock();
                    cs.Close();
                }
                string str = Encoding.UTF8.GetString(ms.ToArray());
                ms.Close();
                return str;
            }
        }
        #endregion

        #region Base64
        /// <summary>
        /// Base64加密
        /// </summary>
        /// <param name="encode">加密采用的编码方式</param>
        /// <param name="source">待加密的明文</param>
        /// <returns></returns>
        public static string EncodeBase64(Encoding encode, string source)
        {
            string result = "";
            try
            {
                byte[] bytes = encode.GetBytes(source);
                result = Convert.ToBase64String(bytes);
            }
            catch
            {
                result = source;
            }
            return result;
        }

        /// <summary>
        /// Base64加密，采用utf8编码方式加密
        /// </summary>
        /// <param name="source">待加密的明文</param>
        /// <returns>加密后的字符串</returns>
        public static string EncodeBase64(string source)
        {
            return EncodeBase64(Encoding.UTF8, source);
        }

        /// <summary>
        /// Base64解密
        /// </summary>
        /// <param name="codeName">解密采用的编码方式，注意和加密时采用的方式一致</param>
        /// <param name="result">待解密的密文</param>
        /// <returns>解密后的字符串</returns>
        public static string DecodeBase64(Encoding encode, string result)
        {
            string decode = "";
            byte[] bytes = Convert.FromBase64String(result);
            try
            {
                decode = encode.GetString(bytes);
            }
            catch
            {
                decode = result;
            }
            return decode;
        }

        /// <summary>
        /// Base64解密，采用utf8编码方式解密
        /// </summary>
        /// <param name="result">待解密的密文</param>
        /// <returns>解密后的字符串</returns>
        public static string DecodeBase64(string result)
        {
            return DecodeBase64(Encoding.UTF8, result);
        }
        #endregion
    }
}
